This device is a locking device to hold one or a plurality of control levers in a stationary, generally neutral position. A spring actuated over center hinged plate is provided with apertures that may constrain the movement of the control lever through interaction with a projecting rod mounted on the control lever. A substantial cutout in the hinged plate is also provided to restrain the movement of the control lever in directions transverse to the fore-and-aft direction of the control lever. Generally the fore-and-aft direction of the control lever will be controlled by the horizontal rod engagement with the hinged plate and transverse movement of the control rod will be restrained by the interaction of the hinge plate cutout with the control lever.
The prior art includes devices that restrain the movement of the control levers. The most obvious types of devices utilize spring loaded detents that may be overridden by an operator when the detented lever is displaced with a certain degree of force. shift levers of automobiles often are guided by a shift gate that assists in proper gear selection. These gates have been designed in certain cases to positively lock out given gears that are not engaged during normal driving. Reverse gear would be an example.
Shift levers have also been designed where a latch mechanism has been incorporated into the lever that would be fingertip controlled to release a lever. This also prevented inadvertent gear shifts.
The closest prior art known by the Applicant involves a transmission lever lockout device where a spring biased plate having a slot formed in the active portion so as to make a U-shape plate can be flipped over to engage the shift lever and prevent relative fore-and-aft displacement.
The device does not positively prevent the movement of the lever as the lever would still be free to move horizontally through the slot in the plate. A device also relevant to this invention is the invention assigned to the same assignor of this invention entitled POSITIVE LEVER LOCATION MAINTENANCE TRAP. That device utilized a flip-over hinged plate identical to the device of this invention. However it only prevented fore-and-aft movement of the control lever and allowed the lever to move transversely to the fore-and-aft plane.
In off highway construction equipment such as an articulated four wheel drive loader having a boom mounted hydraulically operated scoop at the front end thereof it is occasionally necessary to maintain the levers controlling the scoop hydraulics in a neutral position. This is oftentimes necessary when the vehicle is being serviced and the scoop would be at rest on the ground. With the levers restrained in neutral an accidental jostling of them such that the scoop is moved may be prevented. This invention is directed toward providing a positive control lever restraint device that prevents a control lever from being moved into any quadrant when the lever is engaged.
It is also occasionally desirable to maintain a hydraulic control lever in neutral when the host vehicle is being driven, towed on the road or towed on a trailer. Thus a device such as this invention, that would not be disengageable by vibration is desirable. The spring of this apparatus will tend to keep the device engaged in situations where normal vibrations may rattle a lever without the device out of a neutral position.
The instant invention includes a plurality of advantages that make it more desirable than the prior art known to the Applicant. Among these advantages is that the device will positively lock the control lever in a neutral position relative to the lever's path of normal travel, whether the normal travel is in a fore-and-aft plane, a plane transverse to the fore-and-aft plane, or any direction between these two extremes.
Another advantage is that the horizontal rod portion is removable from the control lever. This allows the control lever dust boot to be taken off and replaced over the handle of the control lever rather than necessitating the complete removal of the lever to replace the boot or gain access to the lever fulcrum cover box.
Another advantage of this device is that the spring tension will be predictable in both the engaged and disengaged positions. When engaged the hinged portion is prevented from going beyond a horizontal deployment by the arcuate rod stop fastended to the control lever. Also, when disengaged the hinged portion is prevented from going beyond a predetermined point. As these engaged and disengaged positions are predeterminable then a spring with appropriate characteristics, primarily length and tension can be selected. Spring selection would yield a spring that would always be under some tension thus preventing it from being inadvertantly disengaged.
Another advantage is that the structure of the horizontal rod includes an arcuate rod stop that functions to locate the horizontal rod and also to provide increased strength in the control lever in the area where the control lever has been drilled through to accept the horizontal rod. As stated earlier the arcuate rod stop also functions as a limiting means to support the hinged plate when the hinged plate is in position around the control lever.
Another advantage is that this invention can be retrofitted to unequipped machines with only minimum modifications of the machine. The device is inexpensive to manufacture yet capable of being sturdily constructed to provide a control lever restraint that prevents the movement of a control lever into any quadrant when the lever restraint is in an engaged position.